Uncovering the inferior fronto-occipital fascicle and its topological organization in non-human primates: the missing connection for language evolution
Brain Struct Funct. 2019-03-07; :
DOI: 10.1007/s00429-019-01856-2
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Sarubbo S(1), Petit L(2), De Benedictis A(3), Chioffi F(4), Ptito M(5), DyrbyTB(6)(7).
Author information:
(1)Division of Neurosurgery, Structural and Functional Connectivity Lab Project,
« S. Chiara » Hospital, Azienda Provinciale per i Servizi Sanitari (APSS), 38122,
Trento, Italy. .
(2)Groupe d’Imagerie Neurofonctionnelle, Institut des Maladies
Neurodégénératives, UMR 5293, CNRS, CEA University of Bordeaux, Bordeaux, France.
(3)Neurosurgery Unit, Department of Neuroscience and Neurorehabilitation, Bambino
Gesù Children’s Hospital, IRCCS, 00165, Rome, Italy.
(4)Division of Neurosurgery, Structural and Functional Connectivity Lab Project,
« S. Chiara » Hospital, Azienda Provinciale per i Servizi Sanitari (APSS), 38122,
Trento, Italy.
(5)École d’optométrie, Université de Montréal, Montreal, QC, Canada.
(6)Danish Research Centre for Magnetic Resonance, Center for Functional and
Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre,
Hvidovre, Denmark.
(7)Department of Applied Mathematics and Computer Science, Technical University
of Denmark, Kongens Lyngby, Denmark.
Whether brain networks underlying the multimodal processing of language in humans
are present in non-human primates is an unresolved question in primate evolution.
Conceptual awareness in humans, which is the backbone of verbal and non-verbal
semantic elaboration, involves intracerebral connectivity via the inferior
fronto-occipital fascicle (IFOF). While non-human primates can communicate
through visual information channels, there has been no formal demonstration that
they possess a functional homologue of the human IFOF. Therefore, we undertook a
post-mortem diffusion MRI tractography study in conjunction with Klingler
micro-dissection to search for IFOF fiber tracts in brain of Old-World (vervet)
monkeys. We found clear and concordant evidence from both techniques for the
existence of bilateral fiber tracts connecting the frontal and occipital lobes.
These tracts closely resembled the human IFOF with respect to trajectory,
topological organization, and cortical terminal fields. Moreover, these fibers
are clearly distinct from other bundles previously described in this region of
monkey brain, i.e., the inferior longitudinal and uncinate fascicles, and the
external and extreme capsules. This demonstration of an IFOF in brain of a
species that diverged from the human lineage some 22 millions years ago enhances
our comprehension about the evolution of language and social behavior.
DOI: 10.1007/s00429-019-01856-2
PMID: 30847641